The Senate last week took millions of dollars from one Coast Guard pocket and this week moved to add even more millions to another one -- seemingly contradictary actions that dramatized the growing military role in civilian law enforcement.

The Senate first slashed the Coast Guard budget by $230 million and then took a big step toward adding $375 million to the Pentagon budget for the Coast Guard right after Congress gave final approval to a military procurement bill that pushes the Navy deeper than ever into the effort to stop drugs from being smuggled into the the United States in planes and ships.

Traditionally, the Coast Guard, which is under the Transportation Department, and the Drug Enforcement Administration, which is under the Justice Department, have been the lead agencies in the government's anti-drug war. But Congress impressed the Navy into the fight despite the objections of Defense Secretary Caspar W. Weinberger, who said the fleet has too much else to do.

The Senate now has asked the the Coast Guard to do even more in the fight against drugs -- while cutting $230 million from its operating account as part of the effort to bring Transportation Department funds under the ceilings set in the Congressional budget resolution.

But Adm. James S. Gracey, the Coast Guard commandant, has warned Congress that if the cut sticks, he will have far fewer people, cutters, planes and radars to combat drug smugglers. Since the $230 million cut must be applied in the current fiscal year, Gracey said the Coast Guard would have to discharge 8,500 uniformed and civilian employees, decommission more than 50 ships and lay up more than 40 aircraft. "It's very destabilizing," Gracey said in an interview.

The Coast Guard still has hope. The House did not slash Coast Guard operating funds in passing its version of the bill, and the service will seek restoration of the $230 million in the upcoming Senate-House conference on the rival bills.

The House yesterday heeded the Coast Guard's pleas and added $100 million to the Pentagon's appropriations bill for Coast Guard operations.

"Nobody is going to argue about defense," said Rep. Silvio O. Conte (R-Mass.), sponsor of the amendment. "You put this in the Transportation bill, and you are competing with Amtrak and mass transit," added Conte, the senior Republican on the House Appropriations Committee.

He also vowed to try to get back the rest of the $230 million cut from the Coast Guard's operating account when he goes to the conference on the Transportation bill.

Meanwhile, on Wednesday, Chairman Ted Stevens (R-Alaska) of the Senate Appropriations defense subcommittee won approval of an amendment to add $375 million to the Pentagon's appropriations bill for the Coast Guard. His proposal would establish a new account called "Coastal Defense Augmentation" to help the Coast Guard buy weaponry for wartime.

With that $375 million, the Coast Guard would buy four C130 transport planes, a 140-foot icebreaking tug and 16 110-foot patrol boats. Coast Guard officials welcomed the extra money but said it would not alleviate their problem of manning ships and planes, because funds for those tasks are in the separate operating account.

The Coast Guard and Pentagon also were pushed closer together in the fiscal 1986 military authorization bill sent to President Reagan this week. It authorizes the Navy to help the Coast Guard in the drug war as long as military missions are not undercut.

Destroyers patrolling the Caribbean, for example, would take on a team of Coast Guardsmen. If a boat suspected of smuggling drugs were sighted by the destroyer or patrol planes, the Coast Guard could ask the Navy to stop the suspect vessel. Armed Coast Guardsmen would board the ship, search it and, if contraband were found, make arrests. The Coast Guardsmen would leave the destroyer and sail the seized vessel to the nearest port. The destroyer would then resume its normal patrolling